Intermittent Fasting and the CrossFit Prescription for Nutrition

The CrossFit nutrition recommendation is to eat meat, vegetables, nuts and seeds, some fruit, little starch, and no sugar while keeping intake to levels that support exercise and not body fat. This focus on quality and quantity is how we reach optimal results in health and performance. However, there are times when sustainability outweighs precision when it comes to diet. The CrossFit Nutrition I online course provides nutrition tactics allowing users to maintain quality and quantity control when precise weighing and measuring and other forms of dietary restriction become counterproductive.

Intermittent fasting is one of those tactics. Intermittent-fasting protocols cycle through different ratios of fasting and eating periods. There are multiple formats for intermittent fasting used within the CrossFit community. The most common protocols are the 16:8 method, the 5:2 method, and the 1:1 method. The 16:8 method has users fasting for a 16-hour window, which leaves an eight-hour eating window. In the 5:2 method, practitioners eat normally for five days and consume 500-600 calories on the two fasting days of the week. The 1:1 method is where one eats normally for one day and fasts the next. Which intermittent-fasting protocol you select depends on your performance and health goals as well as preexisting conditions. Before starting an intermittent-fasting protocol, it is important to weigh the pros and cons.

The Nutrition I course outlines many benefits and potential drawbacks to implementing any one of these intermittent-fasting protocols. Some of the pros include weight loss, lower insulin production, and autophagy — the cleaning out of damaged cells in the body. Some cons include side effects due to the adaptation period and extra stress on the body. One thing to consider when fasting intermittently is that it is not an open invitation to eat unfavorable foods during your eating windows. Abstaining from foods and creating a caloric deficit does not provide you the freedom to eat whatever you want. In reality, you should think of intermittent fasting as a template laid over the CrossFit nutrition recommendations. If you’re not able to precisely weigh and measure, no worries. Try to incorporate intermittent fasting while eating meat, vegetables, nuts and seeds, some fruit, little starch, and no sugar. The intermittent-fasting protocol should provide some level of portion control in addition to the other benefits listed above.

Although intermittent fasting is an effective alternative to weighing and measuring, you’ll get optimal results by combining the protocol with eating whole, natural foods and quantifying intake. Start with your baseline recommendation for intake found in the Nutrition I course macronutrient chart. Then, determine whether any adjustments are necessary given the shortened feeding window. As always, allow at least two weeks for each adjustment, and make sure to track your performance or health goals throughout the process.

Intermittent fasting can be a great way to improve metabolic health, reduce body weight, or deal with eating around work and travel demands, and some have found it to be an ideal approach to improving performance. To determine if this strategy works for you, we recommend starting your intermittent-fasting journey with 30 to 60 days of 12:12 eating. This divides the day into a 12-hour fasting window and a 12-hour eating window with meals spread evenly throughout the eating window. Once you have adjusted to consistently withholding food for 12-hour periods, it will be easier to transition into one of the protocols described above. Determine which one works best for you given your lifestyle and performance goals.